I have not had the time to put together some definitive words about Masks and respirators…sorry… the following is all I have to say...
As a summary , I opine that a body of potential bug customers may benefit from wearing a respirator.
Folks over 50 , with immune compromising conditions who move in crowded areas , probably should wear a mask.. no matter what the pigeon settling info says
Flat surgical masks have little if any protective effect as they are not airtight and should not be used
P95 (US) / P2 (Europe) moulded respirator masks are a very good first defence if fitted and used sensibly (this is why health professionals use them).
The virus is usually transported on a carrier, typically aerosols (watermist) and these masks are very effective in this area.
Moulded paper masks should be restricted to one usage over a limited time frame due to internal moisture build up.
To paraphrase another contributor.. doffing and donning correctly is extremely important.
Once fitted the exterior of the mask should be considered contaminated, so if you grab the front of mask to speak or eat…the whole process is a failure unless you refit and wash your hands or fit a new mask.
P3 respirators are a higher level of protection and in practical terms offer 99% protection.